Most of today's video coder standards use block-based motion compensated prediction because of its success in achieving a good balance between coding efficiency and implementation complexity.
Multiple Description Coding (“MDC”) is a source coding method that increases the reliability of a communication system by decomposing a source into multiple bitstreams and then transmitting the bitstreams over separate, independent channels. An MDC system is designed so that, if all channels are received, a very good reconstruction can be made. However, if some channels are not received, a reasonably good reconstruction can still be obtained. In commonly assigned U.S. patent application Ser. No. 08/179,416, a generic method for MDC using a pairwise correlating transform referred to as (“MDTC”) is described. This generic method is designed by assuming the inputs are a set of Gaussian random variables. A method for applying this method for image coding is also described. A subsequent and similarly commonly assigned U.S. Provisional Application Ser. No. 60/145,937, describes a generalized MDTC method. Papers describing MDC-related work include: Y. Wang et al., “Multiple Description Image Coding for Noisy Channels by Pairing Transform Coefficients,” in Proc. IEEE 1997 First Workshop on Multimedia Signal Processing, (Princeton, N.J.), June, 1997; M. T. Orchard et al., “Redundancy Rate Distortion Analysis of Multiple Description Image Coding Using Pairwise Correlating Transforms,” in Proc. ICIP97, (Santa Barbara, Calif.), October, 1997; Y. Wang et al., “Optimal Pairwise Correlating Transforms for Multiple Description Coding,” in Proc. ICIP98, (Chicago, Ill.), October 1998; and V. A. Vaishampayan, “Design of Multiple Description Scalar Quantizer,” in IEEE Trans. Inform. Theory, vol. 39, pp. 821-834, May 1993.
Unfortunately, in existing video coding systems when not all of the bitstream data sent over the separate channels is received, the quality of the reconstructed video sequence suffers. Likewise, as the amount of the bitstream data that is not received increases the quality of the reconstructed video sequence that can be obtained from the received bitstream decreases rapidly.
Accordingly, there is a need in the art for a new approach for coding a video sequence into two descriptions using temporal prediction and motion compensated prediction to improve the quality of the reconstructions that can be achieved when only one of the two descriptions is received.